The knowledge of source, load, and component AC impedance is important in many applications. For example, in the case of a battery (or other source such as a solar cell, fuel cell, etc.), the knowledge of the battery's Electrochemical AC/Complex Impedance Spectrum (EIS) is important because it gives information on the health of the battery such as state of health (SOH) and other characteristics such as state of charge (SOC). Measuring the EIS such as in the battery case, however, usually requires equipment and is done off-line if interrupting the load operation is not feasible. Thus, it is desired to measure EIS online and in real-time and doing so has many benefits and applications.